1. Field of the Invention
The invention relates to an infinitely variable transmission comprising a support body, at least two peripheral gears which are mounted on the support body or on elements that are mechanically coupled thereto in such a way that the rotating shafts thereof are oriented parallel to each other. The distances between the rotational shafts of the peripheral gears can be adjusted so as to always be located on the outer surface of an (imaginary) cylinder. Said transmission further comprises at least one row of elements which surround the peripheral gears on the outside and with which at least one of the gears engages, and a rotational body, preferably coaxial to the axis of rotation of the (imaginary) cylinder, whose rotary movement is coupled to the rotary movement of the peripheral gears; furthermore to a preferred application of such a transmission and an operating method for the same.
2. Description of the Prior Art
Mechanical infinitely variable transmissions are known, in particular with a level friction ring which surrounds two pairs of bevel gears whose tips are inclined towards each other and which are adjustable in an axial direction with respect to each other. The distances between the two pairs of bevel gears are adjusted in opposite directions for the two pairs, so that the friction ring is always frictionally coupled to the two pairs of bevel gears, but finds different circumferences there. Such a transmission is principally infinitely variable, but it is not possible to transmit forces of all magnitudes with them, because the frictional connection tends to slip.
For this reason, attempts have already been made to work with a positive connection-type coupling. For example WO 98/11364 proposes an open chain, the two ends of which are fixed. On a disk-shaped support there are at least two radially adjustable gears which engage with the fixed chain when the disk-shaped support rotates. The peripheral gears then begin to rotate, and this rotation is transmitted to a central shaft by means of drive shafts. The chain surrounds the axle of the disk-shaped support, approximately along a semicircle. Of at least two gears, at least one therefore engages with the chain, in the transitional range both engage to ensure that no slip is possible. Since the at least two gears, via the drive shafts, and the central axle are coupled to each other, they always rotate at the same speed. However, this causes problems with the chain when several gears engage simultaneously, namely during the adjustment of the radial distance of these gears from the rotating shaft. Since they are not capable of rotating relatively to each other, the distance between their teeth is reduced or increased, and the chain engaged there must break.
With respect to this disadvantage, the lesson drawn from DE 35 01 663 does not lead to any improvement. In this attempt to create an infinitely variable transmission with a positive engagement, a gear wheel with a variably effective radius is used; this can be engaged with a chain. The gear wheel is embodied as a disk-shaped support with several eccentric gears which are radially adjustable in relation to its rotating shaft, in particular by means of levers that can be swivelled in and out. Each of the eccentric gears is freely rotatably mounted in one direction of rotation, but is not freely rotatable in the opposite direction of rotation. This gear wheel is coupled in a rotationally fixed manner to another gear wheel by the chain, whereby the chain can be tensioned by a mechanical system regardless of the effective radius of the gear wheel. A reciprocal relative rotation is possible with the gear wheels known from this example, but only in one direction of rotation. This is why all gears except one must be swivelled against the direction of power transmission if the effective radius is to be adjusted, and so they cannot transmit any power. This means that the entire power has to be transmitted via one single gear. Each individual gear must therefore be designed to transmit the maximum power. Moreover, no braking effect is possible with the above-mentioned transmission, and thus no reversal of the direction of rotation.